Port failsafe watching code to raw avr-gcc

More interrupty now
dustin · Apr 19, 2016 · fa4f41f · fa4f41f
1 parent be2a068
commit fa4f41f
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diff --git a/c/avr/failsafe/Makefile b/c/avr/failsafe/Makefile
@@ -0,0 +1,18 @@
+CC=avr-gcc
+OBJCOPY=avr-objcopy
+MICRONUCLEUS=/Users/dsal/Library/Arduino15/packages/digistump/tools/micronucleus/2.0a4/micronucleus
+CFLAGS=-Wall -Os -DF_CPU=16000000L -mmcu=attiny85
+LDFLAGS=-mmcu=attiny85
+
+failsafe.hex: failsafe.elf
+	avr-objcopy -j .text -j .data -O ihex failsafe.elf failsafe.hex
+	avr-size --format=avr --mcu=attiny85 failsafe.elf
+
+failsafe.elf: failsafe.o
+	${CC} $(LDFLAGS) -o failsafe.elf failsafe.o
+
+clean:
+	rm failsafe.{elf,hex,o}
+
+install: failsafe.hex
+	$(MICRONUCLEUS) --run failsafe.hex
diff --git a/c/avr/failsafe/failsafe.c b/c/avr/failsafe/failsafe.c
@@ -0,0 +1,110 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/wdt.h>
+#include <util/delay.h>
+#include <stdbool.h>
+
+#define PPM_PIN      PB0
+#define OUT_PIN      PB1
+#define BUTTON_PIN   PB2
+#define SHUTDOWN_PIN PB3
+
+// a bit under a second
+#define BUTTON_OVERFLOWS 30
+
+volatile bool disabling = false;
+volatile bool failed = false;
+volatile uint8_t prevb = 0xFF;
+volatile int overflows = 0;
+volatile bool watching_button = false;
+
+
+void isr_svc_button() {
+    if (watching_button) {
+        watching_button = false;
+        TIMSK &= ~_BV(TOIE0); // disable timer overflow
+    } else {
+        watching_button = true;
+        TIMSK |= _BV(TOIE0); // enable overflow interupt
+        TCNT0 = 0;
+        overflows = 0;
+    }
+}
+
+ISR(PCINT0_vect) {
+    wdt_reset();
+
+    uint8_t vals = PINB ^ prevb;
+    if (vals & _BV(PPM_PIN)) {
+        failed = false;
+    }
+
+    if (vals & _BV(BUTTON_PIN)) {
+        isr_svc_button();
+    }
+}
+
+ISR(WDT_vect) {
+    wdt_reset();
+    failed = true;
+}
+
+ISR(TIM0_OVF_vect) {
+    if (++overflows >= BUTTON_OVERFLOWS) {
+        disabling = true;
+        TIMSK &= ~_BV(TOIE0);
+        watching_button = false;
+    }
+}
+
+void writeOut(bool failed) {
+    if (failed) {
+        DDRB |= _BV(OUT_PIN);
+    } else {
+        DDRB &= ~_BV(OUT_PIN);
+    }
+}
+
+void disable() {
+    // Maybe like, a beep or something?
+    PORTB |= _BV(OUT_PIN);
+    _delay_ms(250);
+    PORTB &= ~_BV(OUT_PIN);
+
+    DDRB |= _BV(SHUTDOWN_PIN);
+    DDRB &= ~_BV(OUT_PIN);
+    cli();
+    // No more watchdog
+    _WD_CONTROL_REG = 0;
+    // Stop watching inputs
+    PCMSK &= ~(_BV(PCINT0) | _BV(PCINT2));
+    sei();
+}
+
+int main() {
+    DDRB = _BV(OUT_PIN) | _BV(SHUTDOWN_PIN);
+    PORTB |= _BV(BUTTON_PIN);
+
+    cli();
+    GIMSK |= _BV(PCIE);
+    PCMSK |= _BV(PCINT0);
+
+        // I use the timer later.  Set up 1024 prescaler.
+    TCCR0B |= _BV(CS02) | _BV(CS00);  // 1024 prescaler
+
+    // The watchdog timer is used for detecting failsafe state.
+    wdt_reset();
+    _WD_CONTROL_REG = _BV(_WD_CHANGE_BIT) | _BV(WDE);
+    // Enable WDT Interrupt, and Set Timeout to ~1 seconds,
+	_WD_CONTROL_REG = _BV(WDIE) | _BV(WDP2) | _BV(WDP1);
+    sei();
+
+    for (;;) {
+        // just process interrupts
+        asm("sleep");
+        if (disabling) {
+            disable();
+            disabling = false;
+        }
+    }
+}